One of the most important concepts to critically think about during this course is that of life. What is considered “life”? What is alive and what isn’t? and where is life possible?

Kepler Discoveries

(The Kepler Space Telescope used to make transit-detections of possible planets.)

Recently we have had a slew of detections of nearby planets that may be Earth-like (LINK). Not that it is necessary to have an Earth-like conditions in order to have life, but it may even host life that is similar to ours. (LINK).February 21st 2012 Update: A new detection of an exoplanet just 42 light years away from us! AND, we have made measurements of its atmosphere! Here is the LINK and here is an excerpt from the paper:
“Our solar system contains three types of planets: rocky, terrestrial worlds (Mercury, Venus, Earth, and Mars), gas giants (Jupiter and Saturn), and ice giants (Uranus and Neptune). Planets orbiting distant stars come in an even wider variety, including lava worlds and “hot Jupiters.”

Observations by NASA’s Hubble Space Telescope have added a new type of planet to the mix. By analyzing the previously discovered world GJ1214b, astronomer Zachory Berta (Harvard-Smithsonian Center for Astrophysics) and colleagues proved that it is a waterworld enshrouded by a thick, steamy atmosphere.“.

The Kepler team has put together an excellent video showing all the exoplanets (actually: exoplanet candidates) detected thus far:

Recent ESO Discoveries

These new detections of Earth-like planets are extremely important to help us more accurately evaluate how often Earth-like planets arise. You see, until very recently we really only knew about our solar system and our Earth… ours was the only Earth-like planet out there. And, it is completely impossible to make predictions or statistical evaluations based upon 1 single data point. With one single data point we had to accept the full range of opinions from “There are no other planets like ours, ours is completely unique, the factors that went into the formation of our Earth were so improbable they cannot come together again. And thus, extraterrestrial life is not possible.” to “There are millions of planets just like ours in our galaxy alone, so that life is so probable!”.
Which opinion was right? Well, we still don’t know about the extrerrestrial life part but we can say that the search for Earth-like planets is off to a good start: Here is what the European Southern Observatory recently announced: “Many Billions of Rocky Planets in the Habitable Zones around Red Dwarfs in the Milky Way“! (That exclamation mark is my addition). For my students I STRONGLY RECOMMEND YOU READ THE WHOLE NEWS ARTICLE. This is a pretty breakthrough moment in science and you are living in it.

And What Is Life?

And on the topic of Life, here is a link to finding it in some unexpected places; reminding us to keep an open mind on what and where we consider life to be. (LINK)
The following link is to the Astrobiology Web, a great resource for studying life in extreme habitats. (LINK)

(artists’ concept of a planet orbiting two stars)

The search for life on other planets goes hand in hand with the search for other planets.
Here is a recent article with the discovery that planets may be able to “ping-pong” from one star to another: (LINK) (fun fact, I shared an office with one of the co-authors)!